Patent GB-191029260-A (GB)
Title: Process and Apparatus for the Plastic Reproduction of Objects.
Inventor: SELKE WILLY
IPC: G03F7/00
Filed: 1910-12-16
Granted: 1911-12-14
Abstract: 29,260. Selke, W. Dec. 16, 1909, [Convention date]. Artistic modelling. - In the reproduction of solid objects by means of photogrammetric or stereogrammetric theodolite photographs, identified points are directly determined and located in space on a suitable workpiece by the observation of the photographs. In one method, one component of a stereo pair 2, Figs. 1 and 2, is fixed in position on the support 1, which also carries a universal joint or cardan suspension 7 for a rod or pointer 9. The suspension 7 is adjustable along a guide-scale 8. The photographs are observed by an enlarging stereoscope 4 vertically adjustable on a pillar 5, the pillar itself being horizontally adjustable along the guide 6. The instrument 4 carries an arm 10 having a second cardan suspension 11 for the arm 9. The suspensions 7, 11 are adjusted at a distance f apart equal to the focal length of the lens used in taking the photographs. The point 7 and the plane through the point 11 then corresponds to the lens and focal plane of the taking-camera, and in sighting any particular point of the photograph 2, through the corresponding eyepiece of the instrument 4, the point 11 is automatically adjusted to the corresponding image point in the plane through the point 11; the direction of the rod 9 then gives the direction in space of the corresponding object point. The other photograph 3 of the stereopair is horizontally adjustable, and over the photograph 3 is mounted a sighting-tube 16<a> by means of two supports 14, 15 corresponding to the supports 7, 11. The support 1 carries a graduated extension arm 17, and on this is mounted a graduated arm 18 on which is a slide 20 with a rocking telescope 19 positioned over a central mark. The instrument 4 is moved to sight any particular point on the photograph 2, and the photograph 3 is then adjusted horizontally through the necessary parallactic distance a to bring the same point in view under the other eyepiece. The arm 18 is adjusted at a distance B from the suspension 14 equal to the distance between the objectives when the exposure was made, and the telescope 19 is set over the point on the scale 18 sighted by the telescope 16<a>. The central mark under the telescope 19 than indicates on the arm 18 the distance of the object point in space from the suspension 7, and the telescope 19 is rocked until the rod 9 is located. This gives an object point P on the workpiece 21, which is rotatably mounted on a table 23. The workpiece is modelled by obtaining a series of such points. In lieu of the tube a telescope may be used, and the point P is the point at which the two visual rays of the telescopes 9, 19 intersect. In order to reproduce relief on a flat base having, say, one third the natural relief of the originals, a flat background is placed on the table 23, and a point on the background is localized by the instrument 4 to position the workpiece background. The distance between the suspensions 7, 11 is made equal to one-third of f, so that the point of the tube 9 moves three times the normal distance and the face of the background is correspondingly enlarged three - fold, and as the natural correct depths remain unaltered the relative relief is one-third the natural height. By an alternative method the workpiece background plate 22<a>, Fig. 5, is positioned, and the scale on the slide 18 is set to zero. On locating another point p', say at a reading of 15 in front of the background, the background plate 22<a> is advanced to the reading 10 by means of an auxiliary scale 23<a>, and the relief between the advance position and the plane of p<2> gives the required third of the original relief. Other points for reproduction are similarly obtained.